AUdIoCoUrSeS
Joined: 31 Oct 2002
Posts: 2014
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| Week 9 - MIDI and Recording |
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A really big week here, please answer all completely.
1. Describe the following equipment used by a DJ: Cartridge and stylus, Pickup arm, Turntables, Mixer.
2. Why cannot the output of the cartridge be connected directly to a mixing console?
3. Why is it convenient to DI a synthesizer?
4. Comment on the stereo output of many synthesizers?
5. Why might it be desirable to amplify and mic up a synthesizer, as you would an electric guitar?
6. Comment on the use of loops in recording.
7. Comment on tape loops.
8. Comment on looping using a sampler and sequencer.
9. Why is the sample looped using the sequencer in preference to looping it in the sampler?
10. Comment on the significance of synchronizing the sequencer to multitrack tape.
11. Comment on the suitability of audio sequencers for sample looping.
12. What is timecode?
13. Comment on LTC, VITC and MTC.
14. Comment on MIDI Clock.
15. Why is it desirable to synchronize two MIDI units via MIDI Clock?
16. How does MTC correspond to MIDI Clocks and Song Position Pointers?
17. Why is it desirable to synchronize a sequencer to multitrack tape?
18. Comment on the two stages of building up a recording on multitrack tape with the aid of a sequencer.
19. What is an audio sequencer?
20. Is an audio sequencer suitable as a replacement for a multitrack tape recorder (analog or digital)?
21. Comment on the suitability of an audio sequencer for sample and loop editing?
22. Why is it not straightforward to synchronize an audio sequencer to multitrack tape?
23. What parameters of effects can often be controlled via MIDI?
24. Why would you want to control effects parameters by MIDI?
25. Does MTC come in all the frame rates of SMPTE/EBU timecode?
26. Does MTC contain an address?
27. Does MTC contain a clock?
28. Is MTC useful for synchronizing a MIDI sequencer?
29. Is MTC useful for synchronizing digital audio?
30. Is MTC useful for synchronizing analogue audio?
31. Comment on the difference between standalone hard disk recorders and computer based hard disk recorders.
32. Why is it a problem to use hard disks for long term storage?
33. Onto what media does backup/archival storage take place?
34. What are the advantages of standalone hard disk recorders (compared to tape) for editing?
35. What are the advantages and disadvantages of computer based hard disk recorders compared to standalone hard disk recorders?
36. Comment on the use of Pro Tools as an accessory to multitrack tape.
37. List the common digital multitrack tape formats and describe their characteristics.
38. What is 'formatting'?
39. What are the advantages and disadvantages of digital multitrack compared to analogue multitrack?
40. Compare the maintenance and cleaning of an analogue recorder to that of a digital recorder?
41. Who carries out routine maintenance?
42. Describe how the heads and guides of an analogue machine are cleaned. Mention the materials used.
43. Describe how the pinch roller of an analogue machine is cleaned. Mention the materials used.
44. What are the effects of neglecting cleaning?
45. Why must an analogue machine be periodically demagnetised?
46. What happens if a machine is never demagnetised?
47. What might happen if the demagnetised is operated incorrectly?
48. Why do analogue tape recorders need to be lined up?
49. Do digital recorders ever need to be lined up?
50. Comment on the three elements of line up.
51. Explain the need for monitoring in sync.
52. Why is the sync signal inferior to the playback signal?
53. Why does this matter in track bouncing?
54. Is it possible to edit 2" analogue tape?
55. Is it possible to synchronise two 24-track recorders?
56. Why is it often considered better to use an integrated disk recording system rather than one that uses a personal computer as the user interface?
57. Comment on the presentation of some disk recorders as replacements for tape multitrack recorders.
58. If a tape recorder has 24 inputs and 24 outputs, how many tracks will it have?
59. How many inputs and outputs would a disk recorder need if it was to be a replacement for a 24-track tape recorder?
60. If a disk recording system had two inputs, two outputs, and was capable of twenty-four tracks, what would be its main limitations?
61. What information is stored in the session file?
62. Are session files usually transportable between different systems?
63. Comment briefly on the suitability of SCSI, ATA and Firewire disks for audio recording.
64. What is 'fragmentation'?
65. Comment on archiving to CD-ROM.
66. What are 'virtual tracks'?
67. What is meant by 'edit density'? What are the implications of high edit density?
68. Does the editing and trimming of regions delete audio data from the disk?
69. In editing, what is the difference between 'slip' and 'grid' modes?
70. When might it not be possible to create a crossfade?
71. What is 'bouncing', in the context of mixing?
72. What is meant by 'latency'? What is the difference between DSP processing and host-based processing?
_________________
It's all in the ears. - Learn the concepts not the software.
Audio Courses is a way into the music business for you
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Mon May 02, 2005 3:57 am |
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JohnA
Joined: 20 Jan 2005
Posts: 28
Location: Mid Glamorgan, UK |
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Audio Course
AURT03
Week 9
MIDI AND RECORDING
JohnA (mixindown)
1. Describe the following equipment used by a DJ: Cartridge and stylus, Pickup arm, Turntables, Mixer.
A turntable is the piece of equipment that is used to play the records. They are most commonly used in pairs and in conjunction to a mixer. There are two main types - direct drive and belt drive, both of which are very different. The industry standard is the Technics 1200.
Cartridge is the main component where the needle is mounted. Vibrations from the stylus are converted into an electrical impulse. They're attached to the end of the tonearm.
Stylus: This is the needle, a tiny piece of metal that reads the grooves of the record.
A pick-up arm is the mechanical device consisting of a light balanced arm that carries the cartridge
2. Why cannot the output of the cartridge be connected directly to a mixing console?
The reason that the output of the cartridge cannot be connected directly to the mixing console is because the output from the cartridge is only 5mV (a very weak signal). When a vinyl record is recorded, an RIAA EQ curve is applied to the signal. This curve is used to limit the low frequencies and accentuate the high frequencies as the disk is being made. An opposite EQ curve is applied to the signal when the vinyl record is played back on a turntable. This EQ curve resides in a phono pre-amp, which you will need to purchase to record vinyl from a stereo turntable.
3. Why is it convenient to DI a synthesizer?
Because the sound from the synthesizer does not need to be amplified in any way. Also, by DI’ing the synth, you will not get any background sound as you would if you mic’d the synth up.
4. Comment on the stereo output of many synthesizers?
On many early synthesizers (such as the Korg M1), global or master effects are added to the overall output of the synth. This would be just like plugging the main stereo out into a separate multi-effects unit. Other later models added refinements. These included the ability to switch some sounds so that they did not pass through the effects, or to be able to send a different amount of each sound to the effect at the stereo out.
5. Why might it be desirable to amplify and mic up a synthesizer, as you would an electric guitar?
It might be desirable to amplify and mic up a synth for a number or reasons:
a. You may feel the amp gives the a more organic sound to the synth
b. You may want to capture the ambiance of a room for recording.
6. Comment on the use of loops in recording.
Loops can be used in recording to repeat sections of music that do not require change such as a constant kick drum on a dance track. Loops can be recorded directly as audio or triggered from a sequencer via MIDI. When triggered via MIDI, the audio the loop is made up of remains either on the hard disk of your computer or in the hardware sampler it is being triggered from. Loops have become very popular in recorded music since the explosion of dance music.
7. Comment on tape loops.
A tape loop is a recorded segment or sequence of segments of magnetic tape, which have been spliced end-to-end to form a circle or loop. When played in this form, the tape sound is continuously repeated in a loop. These tape loops can be played forwards, backwards and generally mixed with other sounds to create rhythms and compositions.
8. Comment on looping using a sampler and sequencer.
Loops can be triggered from a sampler by using a MIDI channel in a sequencer. These loops can then be recorded into the sequencer (or on the multitrack tape). Editing loops is made very easy when the loops are recorded into a software sequencer.
9. Why is the sample looped - using the sequencer - in preference to looping it in the sampler?
When you trigger a sample from within a sampler, the only part of the sound that you can guarantee will be in sync with an external sequencer is the starting point of the sample. If the “loop length” of the sample is matched precisely to the tempo of the sequencer, and then the sampler’s clock and the sequencers clock should work fine to keep all the tracks in sync, though there can still be drifting in the timing. However, if the loop length is not precisely matched to the tempo of the sequencer, the sample will need to be re-triggered frequently to keep it in sync with the rest of the tracks in the sequencer. Depending on the length of the loop, this could be done every 4 beats or bar. So if all the other tracks were recorded in the sequencer, it would be better to use the sequencers timing to trigger the sample. This way, the sample will play in perfect time, every time.
10. Comment on the significance of synchronizing the sequencer to multitrack tape.
When a sequencer is synchronized to a multi-track tape recorder, you can record the audio to the multitrack and the performance information of MIDI sound modules / synths to the sequencer. You can then stripe (add a sync tone) to one of the tape tracks with SMPTE / MTC to allow it to be synched to the sequencer. If, at a future stage, you want to edit the performance information in the sequencer, you can do so without any alteration to the audio on the multi-track tape. And as they are synched together, they will always both runs in time with each other. If you wanted to control the sync from the multitrack tape machine, you could do this by connecting a unit such as Philip Rees TS1 that is a MIDI Tape Sync Unit. The multi-track should be the master as it is possible that it will not be able to chase MTC.
11. Comment on the suitability of audio sequencers for sample looping.
Audio sequencers are very suitable for sample looping. Once the loop has been recorded into the audio sequencer it can be manipulated in many different ways. It can be copied, pasted, slowed down or speeded up, reversed etc. Some software sequencing packages take things a little further. Acid Pro 3 from Sonic Foundry is a piece of software that allows you to piece together looping (and non-looping) pieces of audio into a musical whole by automatically aligning them rhythmically and automatically adjusting their length and pitch independently so they match in pitch, key, and timing
12. What is timecode?
A Time Code is an electrical (audio) or digital signal that gives a common timing reference for synching MIDI devices with other electronic devices (MIDI such as sound modules and audio such as multi-track tape recorders).
13. Comment on LTC, VITC and MTC.
LTC
Linear/Longitudinal timecode. LTC is part of the SMPTE protocol. This is a squarewave audio signal and when visualized on a display of some kind, will show hours, minutes, seconds and frames to give a specific positional reference 00:00:00:00: Hours, Minutes, Seconds and frames. It is recorded along the length of the tape in the form of a modulated audio signal. LTC is recorded on a spare audio channel when used on an analogue tape recorder. It can be read at high speeds (but it is not recommended for use with video).
VITC:
Vertical Interval Timecode (pronounced VIT-cee)
This is a second way to record SMPTE (or any other) time code on a video
tape and is better used with video. It places the code “in” the video portion of the signal - in an unused area “above” the active picture, just below vertical sync. VITC offers several advantages:
a. It doesn't use up an audio track, allowing you remix or dub your stereo audio at will.
b. It can be read by the video players at speeds ranging from still frame to about 10 times normal forward or reverse speeds.
MTC:
MIDI Time Code (MTC) is used to keep devices that control some sort of timed performance (i.e., a sequencer and video deck or tape recorder) in sync. MTC messages are an alternative to using MIDI Clocks and Song Position Pointer messages. MTC is essentially SMPTE mutated (using a SMPTE to MIDI Converter for) transmission over MIDI. SMPTE timing is referenced from an absolute "time of day". MTC includes positional information, but because it has to share the MIDI data highway with other information, its data is sent in short bursts -- four to each SMPTE frame. It takes eight of these 'quarter frame' messages to carry enough data to make up one complete set of location data, which means that the receiving MIDI device must read two frames of code before it knows where it's supposed to be.
14. Comment on MIDI Clock.
MIDI Clock or MIDI Sync is a measure of relative time (as apposed to real time). When two devices are connected as master and slave, the master sends out various MIDI messages to the slave in the form of Start, Continue and Stop messages. These MIDI Clocks, called PPQ’s or Pulses Per Quarter-not, are set to the slave at a standard rate of 24 per quarter note. If the master timing were 120 beats per minute, the master would send 120 x 24 notes (2880) to the slave every minute. The slave remembers how many MIDI Clocks has been sent to it since the start of the song and therefore can be Stopped by the master at any point and will continue from that point when requested by the master device. This enables tight timings to be accomplished by both devices.
15. Why is it desirable to synchronize two MIDI units via MIDI Clock?
By synchronizing two MIDI units via MIDI Clock, you insure accurate time keeping between both units.
16. How does MTC correspond to MIDI Clocks and Song Position Pointers?
MIDI Clocks are sent from the master device to the slave in the form of PPQ’s (Pulses Per Quarter) notes. The standard rate is 24 PPQ’s sent to the slave per quarter note. As the master device moves, it sends out pulses to the slave. The slave receives these and moves the appropriate number of pulses, attaining the correct position in sync with the master.
Song Position Pointer (SPP):
When two devices are connected up via MIDI with MTC, the slave must follow the master. Song Position Points keep track of how many 16th notes have elapsed since the beginning of the tune. When a song is stopped part way through, the master sends a Stop message to the slave, which stops. When the tune is resumed, the master sends a Continue message to the slave. The slave looks at how many 16th notes have elapsed since the beginning of the song and goes to that position. The master gives the slave enough time to get to that position and both items continue to play together.
17. Why is it desirable to synchronize a sequencer to multitrack tape?
It is desirable to synchronize a sequencer to multi-track tape because a sequencer would be able to follow and keep in time with the multi-track much easier than the other way around. Multi-track recorders will fluctuate in timing when playing. A sequencer is far more accurate as a slave in this set-up is.
18. Comment on the two stages of building up a recording on multitrack tape with the aid of a sequencer.
First you stripe SMPTE Time Code onto the last track of the multi-track. Then set the sequencer to sync with the multitrack over a MIDI cable. This could be done with a SMPTE Generator that converts SMPTE to MTC. The recording process can now start.
19. What is an audio sequencer?
An audio sequencer is a hardware device (or a software program) that allows you to record and then playback audio files just like on a tape recorder. The audio is converted into a digital signal when stored then reconverted back into an audio signal when listened back to (ADC – DAC). If it is software, the audio files are stored on the hard drive on your computer. Audio sequencing packages allow you to edit your audio recordings in a number of ways as well as adding plug ins to the audio sound and supplying the ability to sync the sequencer to other devices via timecode.
20. Is an audio sequencer suitable as a replacement for a multitrack tape recorder (analog or digital)?
It is not suitable for replacing an analogue multitrack tape recorder. A lot of pro studios still use analogue multitrack tape as they feel that the tape gives a “warmth” to the recording. They also feel that it is easier to mix with analogue sound as aposed to digital sound. Another very important point is that analogue recorders are universal, you can play a tape almost anywhere and find a machine to play it on. With these scenarios in mind, the answer to the above question is no, an audio sequencer is not suitable as a replacement for a multi-track recorder.
As it is really the mixing and the sound quality that is the main issue, an audio sequencer would be a suitable replacement for a digital multitrack tape recorder.
21. Comment on the suitability of an audio sequencer for sample and loop editing?
Audio sequencers are very suitable for sample and loop editing. Many programs such as Cubase SX have dedicated sample editors that are built for the job. You can copy, paste, time stretch, reverse, colour, save and generally manipulate the sample and loop in a large number of ways.
22. Why is it not straightforward to synchronize an audio sequencer to multitrack tape?
It is not straightforward to synchronize an audio sequencer to a multitrack tape because the multitrack varies in its playback speed. If the multi-track is the master, the sequencer will follow it.
23. What parameters of effects can often be controlled via MIDI?
All parameters of effects can be controlled via MIDI.
24. Why would you want to control effects parameters by MIDI?
It would be easier to assign an effect parameter to a fader or knob. That way, you could alter the effect using a fader or knob instead of a computer mouse, which can be tricky at times.
25. Does MTC come in all the frame rates of SMPTE/EBU timecode?
Yes. It covers the 4 frame rates:
a. 24 Frames (film)
b. 25 PAL (European Video)
c. 29.97 (NTSC
d. 30 (Original B&W USA TV Rate)
26. Does MTC contain an address?
Yes. MTC frame address is in binary code
27. Does MTC contain a clock?
Yes. MTC contains a clock that measures time in real time: Hours, Minutes, Seconds, and Frames.
28. Is MTC useful for synchronizing a MIDI sequencer?
Yes. MTC can synchronize a MIDI sequencer to another MIDI device or a device that runs SMPTE.
29. Is MTC useful for synchronizing digital audio?
Yes. MTC can synchronize to another unit, for example, a Dedicated Digital Hard disk Recorder via MTC.
30. Is MTC useful for synchronizing analogue audio?
Yes. MTC can synchronize a MIDI sequencer to another MIDI device or a device that runs SMPTE. A SMPTE Generator may be needed to convert the SMPTE tone to MTC.
31. Comment on the difference between standalone hard disk recorders and computer based hard disk recorders.
A stand-alone hard disc recorder is a recorder that is built to do just that job. It has been optimized in its design to perform hard disk recording with the software and hardware that it came with.
Computers, though very good at recording with audio and MIDI, are built to perform many other functions. Its operating system is in constant demand from other system tasks that can interrupt the recording of audio. Many things can go wrong with a computer-based system. Firstly, you have to make sure that all the hardware and software is compatible. Secondly, you have to get the hardware and software to work together (as more often than not, different manufacturers will make these).
32. Why is it a problem to use hard disks for long term storage?
Hard disks are mechanical and at some point will inevitably fail. When they do fail, it can be costly and time consuming to retrieve the information on them.
33. Onto what media does backup/archival storage take place?
Long term storage of digital information should be done on optical storage such as CD-R, DVD. Long term storage on any rewritable optical storage is not advisable.
34. What are the advantages of standalone hard disk recorders (compared to tape) for editing?
Stand alone hard disc recorders will usually come with software that has been designed to work with that specific hardware. It will have been tried and tested and any major weak points will have usually been ironed out before you get it (before it is released onto the market). Hard disk editing with a sequencing package is similar in many respects to editing on a word processor (which is not difficult). Once you get used to the method of editing, it can be very easy, very creative and very enjoyable.
Editing tape is a very cumbersome task compared to editing on a stand alone hard disk recorder. Also, there are many things that you can do with hard disk editing that would be almost, if not impossible with tape. Things such as copy and paste in seconds reverse single tracks etc.
Another very important editing feature on many hard disk recorders is non-destructive editing. On the Mackie HDR 24/96 for example, you can edit up to 999 times and “step back through” these edit if you feel that the edits you have performed are not to your liking. However, I have found that it’s prudent to “save” as you go along (just in case).
35. What are the advantages and disadvantages of computer based hard disk recorders compared to standalone hard disk recorders?
Advantages of computer based hard disk recorders compared to stand alone hard disk recorders:
a. You can change your software and OS at anytime
b. You have a far bigger choice when purchasing hardware for recording
c. You can keep modifying a computer-based system with the latest connections (firewire, USB 2, different sound cards etc.).
d. You can keep updating a computer based systems speed by updating motherboard, CPU etc.
The disadvantages of computer based hard disk recorders compared to stand alone hard disk recorders:
a. You have to get all the things in the above answer to function properly.
b. You have to keep updating drivers etc. if you find things to be incompatible (new soundcard you may have purchased etc.). This can start a “chain-reaction” of incompatibility that can hinder the smooth flow of recording usually found with stand-alone units.
36. Comment on the use of Pro Tools as an accessory to multitrack tape.
Many recording studios use Pro Tools as a medium to edit tracks on hard disk once the tracks have been recorded onto tape. Many people prefer the warm sound of analogue (especially drums) and will record to tape, then take that and send it into Pro Tools for editing. Pro Tools has been an industry standard for this for many years. Digidesign (owners of Pro Tools) also have a large selection of high quality RTAS and TDM plug-ins. Many of these are based on classic designs such as the Fairchild 670 tube limiter.
37. List the common digital multitrack tape formats and describe their characteristics.
DAT: R-DAT: Digital AudioTape: 73 x 54 mm and just 10.5 mm thick. Uses a rotary head to lay tracks diagonally across across the width of the tape (like a video recorder). The same heads are used for recording and playback.
DASH: (Digital Audio Stationary Head). ½” open reel tape. Same ½” tape is compatible on 24 and 48 track DASH machines. Usually edited by copying the tape tracks to another machine. Record head comes after play head.
ADAT: Alesis Digital AudioTape. Became widely used in both home and professional recording studios. Two or more systems can be connected via lightpipe cable. ADAT digital recorders are eight-track and use S-VHS 1/2 inch tapes.
Tascam DTRS (Digital Tape Recording System) machines are usually found used in broadcasting and post-production situations and can provide up to 108 minutes of 16-bit recording.
38. What is 'formatting'?
Formatting places magnetic markers on a hard drive surface to define the sectors in which data is stored. When you format a hard drive, you erase all its files and prepare it as if it were a new or blank hard dive. Formatting your hard drive will wipe clean your drive just like a new hard drive. Different formatting options include FAT 32 and NTFS systems. This creates a separate 'address book' in each partition for managing files.
39. What are the advantages and disadvantages of digital multitrack compared to analogue multitrack?
Advantages of digital multi-track compared to analogue multi-track:
a. Hard disks are easier to handle and store than the larger analogue multi-track tapes.
b. Easier to maintain
c. Easier to edit on
d. If computer based, you can always add new programs to improve editing and recording features.
e. Easier to move digital information around
Disadvantages of digital multi-track compared to analogue multi-track:
a. Analogue is a more pleasing warmer sound (opinions may differ here)
b. Analogues distortion sounds good (digital distortion can sound terrible)
40. Compare the maintenance and cleaning of an analogue recorder to that of a digital recorder?
Analogue recorders need regular cleaning and maintenance. They need to be demagnetized and realignment needs to be done. On a system such as DASH, you need to get an expert in to clean the heads for you. This is all time and money (and inconvenience as a digital recorder does not require any of this.
41. Who carries out routine maintenance?
The routine maintenance of an analogue recorder is usually carried out by the recording engineer because routine maintenance is fairly easy to do.
42. Describe how the heads and guides of an analogue machine are cleaned. Mention the materials used.
The recording/playback heads and all metallic parts that come into contact with the tape. These, as well as the guides, are usually cleaned by gently rubbing them with lint-free Q-tips that have been dipped in Isopropyl Alcohol. There are other variant cleaners to this but this is the one most often used.
43. Describe how the pinch roller of an analogue machine is cleaned. Mention the materials used.
Isopropyl alcohol should not be used to clean the pinch roller as this can burn into the rubber of the roller. American Recorder S-721H is a product specially made for the job. This will also clean heads, guides and rollers. Again, clean with lint-free Q-tips.
44. What are the effects of neglecting cleaning?
If the cleaning of a multi-track tape recorder is neglected, the metal parts will collect a residual magnetism. This can partially erase any tape that is played on the multi-track. Don’t play the master tape to Sgt. Pepper on this! (Unless you don’t like the album that is).
45. Why must an analogue machine be periodically demagnetized?
An analogue machine must be demagnetized periodically for the following reasons:
a. To remove all permanent magnetism from any iron part of the tape path
b. To avoid distortion during recording and play-back due to permanent magnetism
On the heads.
c. To prevent the reduction of sound quality of a tape due to exposure
to magnetic parts.
46. What happens if a machine is never demagnetized?
If a multi-track machine is never demagnetized, residual magnetism will get so bad that any tape that is played on it will be completely erased. The machine would become unusable. This is the machine that should be used to play back the master tapes of most “Eurovision Song Contest” songs!
47. What might happen if the demagnetized is operated incorrectly?
If demagnetization is not performed correctly on the machine, tracks can be partially erased on any tape that is played on the machine. Additional damage can also be caused to the metal parts of the machine.
48. Why do analogue tape recorders need to be lined up?
Analogue tape recorders need to be lined up mainly for two reasons.
a. To get the best out of the machine and the tape, so that the heads are properly aligned with the tape.
b. To ensure that a tape that is played on one multitrack will play properly on any other.
49. Do digital recorders ever need to be lined up?
No. On a DAT machine for example. You can’t align the heads since they are stationary.
50. Comment on the three elements of line up.
The three elements of line up on an analogue tape recorder are:
Azimuth
Azimuth is the alignment of the heads perpendicular to the direction of tape travel. If the azimuth is misadjusted, any program recorded on both tracks will be played back slightly out of phase.
Zenith
Zenith is the alignment of the heads in the same plane as the tape. If the bottom of the head is kicked out too far, it can cause the top tracks not to be in full contact with the head. The zenith can also be misaligned so that the top of the head is shoved too far out. The head should be aligned so that the tape rides against it with smooth contact to the entire surface.
Wrap
Wrap is the alignment of the head so that the tape is in contact with the head at the center, aligned with the head gaps. The wrap adjustment causes the head to swing in an arc centered on the middle of the head, and moves the center of the head from the left to the right of center, depending on which way you adjust the screw.
51. Explain the need for monitoring in sync.
Monitoring in sync is essential for overdubbing. It enables you to monitor previously recorded material whilst recording new material. In sync mode, the record heads are used to play back previously recorded material.
52. Why is the sync signal inferior to the playback signal?
The sync signal is inferior to the playback signal because the sync signal is played back from the record head and not the play head.
53. Why does this matter in track bouncing?
When you bounce tracks, you are in record mode (using the record head). There will be a delay between the play and record head. Um, I’m not clear on this so I don’t know if this is correct (but I had a go at it).
54. Is it possible to edit 2" analogue tape?
Yes. ½” splice tape is recommended to do the joins on 2” tape.
55. Is it possible to synchronize two 24-track recorders?
Yes. You can lock two 24 track analogue tape recorders together but you have to give up one track from each to SMPTE. This means that you will only be able to record on 46 of the 48 tracks.
56. Why is it often considered better to use an integrated disk recording system rather than one that uses a personal computer as the user interface?
An integrated disk recording system is a system that is built for the job. Contacting the manufacturer can help any technical problems. Problems should be easier to trace, as all components will have been (hopefully) rigorously tested against each other for reliability. This is important if you make a living from using your system.
The user often chooses personal computer parts. The user has to get everything to work in sync together. There will probably be a handbook for each piece of separate hardware that you add to a personal computer. It can be far more difficult to solve any problems that may arise when using a personal computer.
57. Comment on the presentation of some disk recorders as replacements for tape multitrack recorders.
Some disk recorders are presented as being far easier to use and maintain than multi-track recorders. There are some, again, like the Mackie HDR 24/96, that are very similar in many respects in its presentation to a multi-track tape machine. You can use “scrub” to find a portion of a track and functions such as start; stop, rewind etc. are very similar to a tape recorder in look and feel.
58. If a tape recorder has 24 inputs and 24 outputs, how many tracks will it have?
A tape recorder with 24 inputs and 24 outputs will have 24 tracks.
59. How many inputs and outputs would a disk recorder need if it were to be a replacement for a 24-track tape recorder?
It would have to have the same number of inputs and outputs that a 24-track tape recorder has which are 24.
60. If a disk recording system had two inputs, two outputs, and was capable of twenty-four tracks, what would be its main limitations?
The main limitations would be:
a. You would only be able to record a maximum of two tracks at a time (no good to record a live band)
b. You would not be able to route more than two individual outputs to outboard multi-effects an any one time.
61. What information is stored in the session file?
Information that is stored in a session file includes the title of the project you are currently working on, the names of individual audio and MIDI files, all editing and plug-in information,
62. Are session files usually transportable between different systems?
No, the session files are not usually transportable between different systems.
63. Comment briefly on the suitability of SCSI, ATA and Firewire disks for audio recording.
Comments on the suitability of the following for audio recording:
SCSI: Has a fast data-transmission rate. It’s easy to transfer data from one computer to another (this is done via a cable connection). Up to 15 additional SCSI devices can be connected to one unit, all run from a single IRQ on a PC.
ATA (IDE): Controllers are integrated so they can be connected directly to the motherboard. Pricing is very comparable to other systems. Spindle speeds are 7200 and 10,000rpm. Fast spindle speed is an advantage when recording and monitoring audio.
Firewire (IEEE 1394): supports Isochronious data. This ensures that the audio is delivered at a guaranteed rate. Support for hot plugging. Supports up to 63 devices on a single bus. Various speeds 100, 200, 400 and 800 Mbps are backward compatible.
64. What is 'fragmentation'?
Refers to the condition of a disk in which files are divided into pieces scattered into different areas all around the disk. File system starts out with all or most of its files contiguous (very close to each other), and becomes more and more fragmented as a result of the file creation and deletion over time. Fragmentation occurs naturally when you use a disk frequently, when you are creating, deleting, and modifying files. At some point, the operating system needs to store parts of a file in noncontiguous clusters. This is entirely invisible to users, but it can slow down the speed at which data is accessed by the user because the disk drive must search through different parts of the disk to put together a single file. So fragmentation makes the information on the disk slower to read.
65. Comment on archiving to CD-ROM.
CD-ROM is one of, if not the most, reliable medium to archive your audio and data onto. They are far more reliable than hard disk drives (especially for long term storage). They can also be purchased in “bite sized chunks” instead of purchasing 100Gig hard drive to back up everything on, you can purchase just a few CD-ROM’s and make multiple copies. These can be stored at various locations to guard against loss or damage of just a single copy. CD-ROM’s also have the advantage that once you have written your audio/data, they cannot be re-written over. It has been commented that the information on a CD-ROM will last for up to 100 years. (I have made some recordings and put them in storage and will get back to you on this once I have checked out whether or not this is true). Just one other note, if it hasn’t been backed up at least twice, it hasn’t been backed up!
66. What are 'virtual tracks'?
If you have a multitrack tape recorder that is sync’d to control a sequencer, which in turn is synched to a drum machine. The audio outputs of the drum machine can be connected to a mixing desk. In this setup, the outputs from the drum machine are called virtual tracks.
67. What is meant by 'edit density'? What are the implications of high edit density?
Edit density refers to where data is stored on a hard disk. When a lot of editing and storing is performed to the same audio/data, this audio/data gets spread out into more and mores sections of the hard drive. The more scattered these files become, the harder it is for the system to read them. High edit density refers to files that have had a lot of editing and storing done to them. The implications are that tracks with high edit density are more difficult for the system to read and consequently play back simultaneously (which is the whole point of recording multiple tracks).
68. Does the editing and trimming of regions delete audio data from the disk?
No. Regions are visuals created in the sequencing software for the user to see and be able to edit parts of the recorded waveform.
69. In editing, what is the difference between 'slip' and 'grid' modes?
When you move files in your sequencing package in grid mode, the files are “snapped” to an onscreen grid, to settings that the user can define. This helps with quantizing your recordings.
Slip mode, frees up the restrictions of grid mode, enabling you to move a file to any location on the sequencing screen.
70. When might it not be possible to create a crossfade?
It would not be possible to perform a crossfade if tow regions do not have any audio content at the corssfade points.
71. What is 'bouncing', in the context of mixing?
In mixing, bouncing is the grouping a number of tracks onto an available track or pair of tracks.
72. What is meant by 'latency'? What is the difference between DSP processing and host-based processing?
Latency is a measure of how long, on average, it take to get a response from something. Latency is noticed as a delay in the signal from when it is played to when it is heard.
JohnA
http://www.soundonsound.com/sos/1995_articles/sep95/midibasics2.html
http://www.webtechgeek.com/How-to-Format-a-Hard-Drive.htm
http://www.soundonsound.com/sos/mar99/articles/synthfx.htm
http://www.soundonsound.com/sos/mar00/articles/miditime.htm
http://members.aol.com/uniquenyc/key25.htm
http://members.aol.com/uniquenyc/key1.htm
http://www.borg.com/~jglatt/tutr/whatsseq.htm
http://www.partition-manager.com/overview_details/defragmenter.htm?sourceID=MainPage
http://www.midi-classics.com/h/h27587.htm
http://www.mintekdigital.com/glossary/glossary_s.html
http://www.microsoft.com/athome/security/update/wherebackup.mspx |
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Fri May 06, 2005 4:21 pm |
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rachelh
Joined: 16 Jan 2005
Posts: 35
Location: Trinidad WI |
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Week 9 - MIDI and Recording
Submitted by: Rachel
1. Describe the following equipment used by a DJ: Cartridge and stylus, Pickup arm, Turntables, Mixer. [5]
THE STYLUS AND CARTRIDGE
The stylus is the element in a phonograph cartridge that rides in the groove of a record. It consists of a small arm called the cantilever and the stylus tip. They are designed to be able to move in to orthogonal directions at once. (Orthogonal refers to two [or more] phenomena that can exist in the same medium at the same time and not interfere with one another. The vertical and horizontal motion of a properly working stylus tracking a record groove is an example of orthogonal motion.) it is in general the needle used to read the grooves in the record. The stylus sends the vibrations picked up from the vinyl to the cartridge where they are then transformed into electrical impulses allowing sound to be produced. The cartridge most commonly used today because of it's overall durability and sound quality is the Stanton 500AL.
PICK- UP ARM:
The Pick-up arm or the headshell is attached to the end of the tone arm providing protection and a site for the cartridge and stylus to fix onto. A protruding hook can also be seen on the headshell, this is simply used to move the stylus to a different position on the vinyl carefully without scratching it.
TURNTABLE
The turntable is the rotating plate that the record is placed on.
MIXER
The mixer as the name implies, is used to mix namely crossfade the signals from the turntables that are plugged into it.
2. Why cannot the output of the cartridge be connected directly to a mixing console?
The output of the cartridge cannot be connected directly to a mixing console because the input impedance of a mic input is about 2 kilo ohms whilst the input impedance which is required for a cartridge is 47 kilo ohms making the input of the mic input too low for the cartridge also, the output level for a cartridge is around 5mV whilst line level for a console is around .775V.
3. Why is it convenient to DI a synthesizer?
It is convenient to directly insert a synthesiser because if the Synth is not directly inserted it would then have to be recorded meaning that the synth would have to be connected to an amp which in turn is routed to a loudspeaker then, the sound is picked up by a microphone. Which in itself is a lot of work also ambient noise will be a factor in the recording.
4. Comment on the stereo output of many synthesizers?
The stereo output found on many synthesisers is what would allow a synth to be directly inserted into a mixing console.
5. Why might it be desirable to amplify and mic up a synthesizer, as you would an electric guitar?
It may be desirable to amplify and mic a synthesiser as you would an electric guitar if it cannot be directly inserted into a mixing console. It is convenient to directly insert a synthesiser because if the Synth is not directly inserted it would then have to be recorded meaning that the synth would have to be connected to an amp which in turn is routed to a loudspeaker then, the sound is picked up by a microphone. Which in itself is a lot of work also ambient noise will be a factor in the recording.
6. Comment on the use of loops in recording.
the use of loops in recording is an example of an editing technique that is used to maximise the available RAM and disk based memory of a system. Through this technique, a sample that occupies a finite memory space in RAM can be sustained for long periods of time [well past the original length of the signal] thereby preventing the sound from abruptly stopping while the key on a MIDI keyboard is still held down. [1]
7. Comment on tape loops.
Tape loops are created by splicing the area of the loop and piecing the spliced area back together with tape, then this edit/ loop can be played looped as desired.
8. Comment on looping using a sampler and sequencer.
Looping using a sampler can be done the same way that is done using a sequencer, the area is selected and a loop command is applied with details on duration etc.
9. Why is the sample looped using the sequencer in preference to looping it in the sampler?
The sample looped using the sequencer would be preferable to that of the sampler because the sequencer allows for graphical representation of the waveform thus making edit points easy to pick out.
10. Comment on the significance of synchronizing the sequencer to multitrack tape.
The significance of synchronizing the sequencer to multitrack tape would to be to control the speed and relative positions on the tape to accurately follow one specific transport/ designated master.
11. Comment on the suitability of audio sequencers for sample looping.
An audio sequencer is suitable for performing sample and loop editing. It has the ability to edit sequenced tracks. Editing functions and capabilities differ from one sequencer to another but sample and loop editing can be deemed basic functions.
12. What is timecode?
Timecode is the standard method of interlocking audio, video and film transports that makes use of a code developed by the Society of Motion Picture and television Engineers [STMPE]. The use of this STMPE time code allows for the identification of an exact position on a tape or within a media program by assigning a digital address to each specified length. This address code cannot slip, and always retains its accuracy between 1/24th and 1/30th of a second [dependant on the media type and the standards being used]. The specified tape segments are called frames, a term taken from film production. And the time code address is the tag given to every audio and video frame and is represented by an 8 digit code highlighting hours:minutes:seconds:frames i.e. 00:00:00:00 [1]
13. Comment on LTC, VITC and MTC.
LTC, VITC and MTC are all examples of time code. LTC [Longitudinal Tome Code] and VITC [Vertical Interval Time Code] are the two major systems that existfor encoding time code onto magnetic tape. LTC encodes a biphase time code signal onto the analogue audio or cue track in the form of a modulated square wave at a bit rate of 2400 bits/second. In most situations LTC code is preferred for audio. Electronic music and midlevel video production and it’s a more accessible and cost effective protocol. VITC is used by major video production houses, it makes use of the same SMPTE and user code structure as LTC but is encoded onto videotape in an entirely different manner that is, it actually encodes the time code information into the video signal itself. MTC or Musical Instrument Digital Interface Time Code was developed for electronic music studios, project studios and all other production environments to have a cost effective and easily implemented way to translate time code into time-stamped MIDI messages and back. It allows for time code to be distributed throughout the MIDI chain to devices that are able to understand and execute MTC commands. [1]
14. Comment on MIDI Clock.
The MIDI Clock is not related to SMPTE time code or any external reference. Ideally it is the built in and often transparent protocol for synchronising all of the timing elements of each MIDI device within a connected system to a master timing clock. This protocol operates by transmitting real time messages over standard MIDI cables. As with all types of synchronisation, one device must be designated the master device in order to provide timing information to which all other slaved devices are locked. [1]
15. Why is it desirable to synchronize two MIDI units via MIDI Clock?
It is desirable to synchronise two MIDI units via MIDI clock in order to provide timing information so that the both devices would be in time with each other. [1]
16. How does MTC correspond to MIDI Clocks and Song Position Pointers?
Song position pointers (SPPs) allow a sequencer or drum machine to be synchronised to an external source such as a tape machine from any measure position within a song. Although SSPs are used less often than MIDI Time Code [MTC], it can synchronise a location in a MIDI sequence in measure to a matching position point on an external device such as a drum machine or a tape recorder, by providing timing reference that increments once for every six MIDI clock messages with respect to the beginning of a song. [1]
17. Why is it desirable to synchronize a sequencer to multitrack tape?
It is desirable to synchronise a sequencer to multitrack tape to control the speed and relative positions on the tape to accurately follow one specific transport/ designated master.
18. Comment on the two stages of building up a recording on multitrack tape with the aid of a sequencer.
The two stages of building up a recording on multitrack tape with the aid of a sequencer would be firstly to record the tracks on the sequencer then, export them to tape onto the tracks with the use of a synchroniser to allow for accuracy of timing and MIDI information encoded.
19. What is an audio sequencer?
An audio sequencer is a digital device that is used to record, edit and output MIDI messages in a sequential fashion. These sequential messages are generally arranged in track based format that follows the modern production concept of locating separate instruments and/ or instrument voices onto separate tracks.
20. Is an audio sequencer suitable as a replacement for a multitrack tape recorder (analog or digital)?
An audio sequencer is suitable as a replacement for a multitrack tape recorder. As the audio can be recorded on the memory used by the sequencer whether it is a hardware sequencer or a software based one. Sequencers are capable of recording, editing and outputting MIDI messages. Thus a sequencer is a very capable audio recording/ editing device.
21. Comment on the suitability of an audio sequencer for sample and loop editing?
An audio sequencer is suitable for performing sample and loop editing. It has the ability to edit sequenced tracks. Editing functions and capabilities differ from one sequencer to another but sample and loop editing can be deemed basic functions.
22. Why is it not straightforward to synchronize an audio sequencer to multitrack tape?
It is not straightforward to synchronise an audio sequencer to multitrack tape due to the process that has to be adhered to make this happen. Before the tape can be used it has to be formatted.
23. What parameters of effects can often be controlled via MIDI?
The parameters that can be controlled by MIDI include transport, panning, volume, stereo/mono whilst the effects are reverb, echo, looping and so on virtually all parameters and effects can be controlled by MIDI.
24. Why would you want to control effects parameters by MIDI?
I would want to control effects parameters by MIDI because it would be easier to adjust these settings.
25. Does MTC come in all the frame rates of SMPTE/EBU timecode?
MTC comes in all the frame rates of SMPTS/ EBU timecode, which in turn equates to four rates:
I. 30 fps
II. 25 fps
III. 24 fps.
IV. 29.97 fps (30 fps drop frame)
26. Does MTC contain an address?
MTC contains an address, which in essence a time based code with commands. [1]
27. Does MTC contain a clock?
MTC indeed does not contain a clock - Timecode is the standard method of interlocking audio, video and film transports that makes use of a code developed by the Society of Motion Picture and television Engineers [STMPE]. The use of this STMPE time code allows for the identification of an exact position on a tape or within a media program by assigning a
digital address
to each specified length. This address code cannot slip, and always retains its accuracy between 1/24th and 1/30th of a second [dependant on the media type and the standards being used]. The specified tape segments are called frames, a term taken from film production. And the time code address is the tag given to every audio and video frame and is represented by an 8 digit code highlighting hours:minutes:seconds:frames i.e. 00:00:00:00 [1]
28. Is MTC useful for synchronizing a MIDI sequencer?
MTC is indeed useful for synchronising a MIDI sequencer, MTC can be utilised to synchronise a MIDI sequencer to any device in a MIDI chain that is SMPTE compliant. [1]
29. Is MTC useful for synchronizing digital audio?
MTC is indeed useful for synchronising digital audio; an audio sequencer can be sequenced to an external device such as a digital hard disk recorder.
30. Is MTC useful for synchronizing analogue audio?
MTC is indeed useful for synchronising analogue audio.
31. Comment on the difference between standalone hard disk recorders and computer based hard disk recorders.
Standalone hard disk recorders refer to those that incorporate all needed recording peripherals into once compact unit whilst computer based hard disk recorders use software [stored on the computer] in conjunction with peripherals that can be attached to the computer via one of its ports or through the use of an audio interface. The difference between standalone and computer based hard disk recorders lie in their respective definitions also in the fact that standalone systems are designed around recording music and audio and thus are made especially for that purpose, whilst computer based systems lack that stability and if problems arise there is no liability as the computer manufacturer, the computer peripheral manufacturer, and the audio software developer could only get you that far.
32. Why is it a problem to use hard disks for long-term storage?
It is a problem to use hard disks for long-term storage, as the life of archived data on disk is yet to be determined thus, there is a risk involved.
33. Onto what media does backup/archival storage take place?
Backup/archival storage can take place on the hard disk itself, CD ROM, or even tape. In terms of price, CD ROMS would be the cheapest medium, followed by disk then tape. CD ROM storage provides the best-assured means of storage.
34. What are the advantages of standalone hard disk recorders (compared to tape) for editing?
The advantages of standalone hard disk recorders (compared to tape) for editing are that standalone disk recorders allow for much more editing potential which can be done on the disk itself whilst with tape, one has to go through the process of manually cutting out the unwanted parts and piecing the tape back together – which can be detrimental if not successfully done that is, if the edit points were not accurately chosen.
35. What are the advantages and disadvantages of computer based hard disk recorders compared to standalone hard disk recorders?
The advantages and disadvantages of computer based hard disk recorders compared to standalone hard disk recorders are: -
I. Standalone systems are designed around recording music and audio and thus are made especially for that purpose, whilst computer based systems lack that stability and if problems arise there is no liability as the computer manufacturer, the computer peripheral manufacturer, and the audio software developer could only get you that far.
II. Price- PC systems are much more affordable than standalone systems.
III. Computer based systems are susceptible to viruses, crashing and other technical problems associated with Operating Systems, latency and other problems that affect the efficiency computer based systems.
36. Comment on the use of Pro Tools as an accessory to multitrack tape.
Pro Tools can be an accessory to multitrack tape as a post-recording editing tool.
37. List the common digital multitrack tape formats and describe their characteristics.
The common digital multitrack tape formats are DASH, ADAT, and DTRS.
DASH- Digital Audio Stationary head was designed to be a cut-and-splice format for editing. However in its usage it was found that the edits were not stable and unreliable. Editing DASH is now done via the use of copying between two machines that are synchronised with an offset. Thus two synchronised 24-track machines are more efficient than one 48 track machine.
ADAT- Alesis Digital Audio Tape has a recording time of 60 minutes, is used in budget recording studios, is capable of 8 tracks, multiple machines can be synchronised to produce more tracks, S-VHS tapes are used for recording, the tape needs to be formatted before use, high resolution versions are available.
DTRS- Digital Tape Recording System has a recording time of 108 minutes, is used namely for film post-production and broadcast post production, is capable of 8 tracks, multiple machines can be synchronised to produce more tracks, Hi-8 tapes are used for recording, the tape needs to be formatted before use, high resolution versions are available.
38. What is 'formatting'?
Formatting is the process by which the tape is formatted in order to be used – usage is dependent on formatting. The actual formatting process involves laying down time code, as well as what type of formatting would be used that is, DASH, ADAT or DTRS. The tape can be pre formatted which will take a considerable amount of time to achieve [this process is recommended for DASH recorders], it can also be formatted during the recording on DAT recorders but is only done if the entire tape is being recorded at one time without stopping.
39. What are the advantages and disadvantages of digital multitrack compared to analogue multitrack?
The advantages of digital multitrack over analogue multitrack are
I. System Price- less expensive except for DASH based systems and the tapes are also less expensive
II. Quality of Sound- analogue sound, though characteristically warm, still has the inherency of being less clear
The disadvantages of digital multitrack over analogue multitrack are
I. The adherent lack of compatibility between machines, whilst once properly aligned, an analogue recording played on can be any analogue machine.
II. Because digital multitrack is inherently digital it is susceptible to program failures and other inherently digital malfunctions and glitches.
40. Compare the maintenance and cleaning of an analogue recorder to that of a digital recorder?
The maintenance and cleaning of an analogue recorder can be done by the engineer him/ herself whilst a trained technician has to be brought in to clean a digital recorder.
The cleaning / maintenance procedure for an Analogue Recorder:
I. The heads, which are metallic and guides, can be cleaned using cotton and isopropyl alcohol. All other parts that come into contact with the tape can be cleaned via this method.
II. The pinch wheels which are made up of plastic can be cleaned using alcohol but it is better practice to use rubber cleaner or maybe a non abrasive household cleaner- a small amount of cleaning solution is often needed.
III. Aligning of the tape heads adjusting: azimuth, playback level and so on
The cleaning / maintenance procedure for a Digital Recorder:
I. A trained technician is brought in on average of every 6 months
II. Heads are cleaned not with cotton as with the analogue recorder but with a chamois-leather cleaning tool and wiped in a horizontal motion only
III. Alignment is done with special tools inclusive of a computer
41. Who carries out routine maintenance?
Routine maintenance for the analogue recorder can be done by the engineer and for the digital recorder a technician is called in on average of every 6 months to conduct maintenance.
42. Describe how the heads and guides of an analogue machine are cleaned. Mention the materials used.
The heads and guides of an analogue machine can be cleaned using cotton and isopropyl alcohol using gentle strokes as well as all other parts that come into contact with the tape.
43. Describe how the pinch roller of an analogue machine is cleaned. Mention the materials used.
The pinch wheels/ roller of an analogue machine is made up of a rubbery plastic can be cleaned using alcohol but it is better practice to use rubber cleaner or maybe a non abrasive household cleaner- a small amount of cleaning solution is often needed.
44. What are the effects of neglecting cleaning?
The effects of neglecting cleaning would be a decrease in performance from the machines and can be especially noticed on playback and the quality of sound recorded.
45. Why must an analogue machine be periodically demagnetised?
An analogue machine should be periodically demagnetised or degaussed because after a period of time the of use, magnetic residue builds up on the metal parts of the recorder causing the partial erasing of any tape that is played on the recorder. A special demagnetiser is used which requires proper training to use or the situation may be made drastically worse.
46. What happens if a machine is never demagnetised?
If a tape machine is never demagnetised then, all the residue magnetism present on the metal parts of the recorder will ensure that any tape played on the recorder would be completely erased.
47. What might happen if the demagnetised is operated incorrectly?
If the demagnetised is operated incorrectly the situation that is, the involuntary erasure of tapes will be made worse.
48. Why do analogue tape recorders need to be lined up?
Analogue tape recorders need to be lined up to ensure that the tape can be playable/ compatible with any other analogue recorder and also, that the best possible sound can be recorded and played back from the tape. Aligning an analogue recorder ensures the proper working of the equipment at hand.
49. Do digital recorders ever need to be lined up?
Digital recorders are indeed lined up. This is done by a trained technician, who utilises special tools inclusive of a computer to complete this task.
50. Comment on the three elements of line up.
The three elements of line up are:
I. Azimuth - Azimuth refers to the head’s tilt in the plane parallel to the tape. The head gap should be perpendicular to the tape so that all track gaps are electrically in phase with each other.
II. EQ-the 10 kHz tone on the calibration tape is played and this adjusts the EQ.
III. Bias- High frequency signal used in analogue recording to improve the accuracy of the recorded signal and to drive the erase head. Bias is generated by a bias oscillator.
51. Explain the need for monitoring in sync.
The need for monitoring in sync arises from the necessity to be able to listen to or monitor previously recorded tracks whilst performing an overdub. The gap between the record and playback heads makes this difficult as it causes a delay in the recorded signal; thus, the record head is used as a playback head – in a process known as sync output. This sync output is not of the best sound quality as the recording head is not meant for playback but, the sound produced is good enough for monitoring and thus servs this purpose.
52. Why is the sync signal inferior to the playback signal?
The sync signal is inferior to the playback signal because the recording head is not meant for playback but, the sound produced is good enough for monitoring and thus serves this purpose.
53. Why does this matter in track bouncing?
Track bouncing in the context of mixing refers to the process by which similar tracks are combined onto one to free up other tracks and make them available for additional recording. In bouncing, the inferiority of the sync signal is notable because it cannot be ‘bounced’ as it is inferior in sound quality.
54. Is it possible to edit 2" analogue tape?
Cut editing or destructive editing is traditionally done on ¼” monophonic and stereophonic tapes – multitrack tapes, those consisting of four or more tracks are not cut edited. Thus, 2” analogue tape can be edited.
55. Is it possible to synchronise two 24-track recorders?
It is very much possible to synchronise two 24- track recorders, this can be done to increase the number of available tracks for recording audio. When an analogue project is recorded in this format it is seen is being more convenient for editing to copy the tapes to a Sony 3448 [which is faster and more receptive than synchronised analogue machines] thus, making the mixing process faster and smoother in the running.
56. Why is it often considered better to use an integrated disk recording system rather than one that uses a personal computer as the user interface?
It is often considered better to use an integrated disk recording system rather than one that uses a personal computer as the user interface because of the inherent lack of liability when problems arise in a PC based system, integrated disk recording systems are primarily built for the purpose of creating and editing music thus, liability is in the hands of the manufacturer if any problems arise.
57. Comment on the presentation of some disk recorders as replacements for tape multitrack recorders.
The presentation of some disk recorders as replacements for tape multitrack recorders resound around the fact that the disk recording machines as well as the disks are cheaper than the tape machines and the associated tapes and more information can be stored on disk than on tape.
58. If a tape recorder has 24 inputs and 24 outputs, how many tracks will it have?
A tape recorder that has 24 inputs and 24 outputs would have 24 tracks
59. How many inputs and outputs would a disk recorder need if it was to be a replacement for a 24-track tape recorder?
A tape recorder having 24 inputs and 24 outputs would have 24 tracks. For a disk recorder to be a replacement for a 24- track tape recorder, the number of inputs and outputs would be dependent on the speed of the disk as in theory this defines the number of tracks that can be allocated, I would think that the minimum number of inputs and outputs would be 2 each it is all dependent on the speed of the disk, if the disk is fast enough to process additional data, 24 inputs and outputs can be utilised or even more. But generally disk recorders do not have a set precedent with respect to a correlation between the number of inputs and outputs being the same.
60. If a disk recording system had two inputs, two outputs, and was capable of twenty-four tracks, what would be its main limitations?
The main limitations of a recording system that has two inputs and two outputs and was capable of twenty-four tracks would be the speed of the disk and the capabilities of the processor. The faster the disk in conjunction with the processor is able to retrieve and process data the less the limitations of the disk recording system. As an engineer, the limitations presented my this situation would be not more than two tracks could be recorded at any one time- increasing the duration of the session, the disk speed factor will be what determines the device latency as well as how many edits can be stored as well as virtual tracks and how many processes can take place at any one time.
61. What information is stored in the session file?
In the session file information pertaining to the name of the project, the tracks [how they are assigned], loops/ audio files used and editing which occurred are stored.
62. Are session files usually transportable between different systems?
Session files are usually not transportable between different systems as there is currently no universal compatibility between systems for this format. Thus, if you take one disk cartridge and load it into a disk recording system that is not the same as the one in which the data was originally stored/recorded, there will be problems with respect to reading the data if it is read at all.
63. Comment briefly on the suitability of SCSI, ATA and Firewire disks for audio recording.
SCSI, ATA and FireWire are all interfaces. The SCSI interface allows for a disk to be connected externally to a system or to be daisy chained to a system, ATA does not allow for external disk connection, FireWire however is not a disk, it is as previously mentioned an interface. With respect to audio recording and speed, SCSI is the best medium; ATA and FireWire are not as fast as SCSI.
64. What is 'fragmentation'?
Fragmentation is when data stored on the hard drive is broken up into pieces, due to data being moved, re-written or deleted. Fragmentation slows down the disk as a file may be broken up into many pieces and instead of being stored continuously onto adjacent clusters and sectors, thus, the disk head may have to skip over a few sectors to allocate a file in its totality slowing down file retrieval and processing.
65. Comment on archiving to CD-ROM.
Archiving to CD-ROM is a very effective system. CD ROM discs are in expensive and are a good medium for storing data only problem being that it is not suitable for storing immensely large amounts of data as the limits are usually beneath 700 megabytes. Storing data on a DVD disc can be a solution to this problem.
66. What are 'virtual tracks'?
A virtual track is a track stored in memory that is synchronised with the tracks that actually exist. Virtual tracks allow disk-based recorders to store many variations of a track or many recorded tracks – as much as the memory permits, these tracks can be often switched with real tracks when need arises.
67. What is meant by 'edit density'? What are the implications of high edit density?
The term ‘edit density’ refers to the number of regions in on the disk that data is stored and their proximity in relation to one another, high density has the effect of slowing a disk down as the information for playback is so scattered that it takes time for the disk heads to locate the data, the higher the edit density, the less amount of simultaneous tracks would be allowed in the playback.
68. Does the editing and trimming of regions delete audio data from the disk?
Editing and trimming of regions does not delete audio data from the disk, it merely silences this data. Thus if the trimmed data is needed it can be easily recalled.
69. In editing, what is the difference between 'slip' and 'grid' modes?
In editing, the slip mode allows clips to be slipped into tracks without adhering to time and measure constraints where as the grid mode is regulated with respect to time and measure.
70. When might it not be possible to create a crossfade?
A crossfade can be created when we have two clips and we want to bring them together and have them flow one into the other seamlessly. It may not be possible to create a crossfade if there is no material before and after the parameters of the fade as it is this material that is needed to create the fade itself.
71. What is 'bouncing', in the context of mixing?
Bouncing in the context of mixing refers to the process by which similar tracks are combined onto one to free up other tracks and make them available for additional recording.
72. What is meant by 'latency'? What is the difference between DSP processing and host-based processing?
Latency is also known as delay. It occurs in the exchange of packets of data from one place to another. In audio, latency is the time that the audio is retrieved from the hard drive then heard or the time that audio is processed then heard with real time effects – it is the time taken for an electronic device to execute the task requested. A device with a high latency takes a longer time to execute a task than a low latency would take.
DSP processing refers to digital signal processing, DSP processing is much faster than host based or computer based processing, as DSP is synonymous with lower incidences of latency. Because DSP based systems are designed around music production [incorporating specially designed hardware chips and dedicated processors], they are designed to cope with audio signals as opposed to normal data that is written and stored onto a computer. Thus making DSP a more compatible medium when recording and playing back music.
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Reference:
1) Modern Recording Techniques – DM Huber, R Runstein
2) Studio Recording Engineer
3) Sound and Recording – F Rumsey, T McCormick
4) Sweetwater.com
5) http://www.djsource.co.uk/tutorials/ |
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Sat May 07, 2005 7:05 pm |
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hoaxwagon
Joined: 28 Feb 2005
Posts: 27
Location: Boulder Creek, CA USA |
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1. Describe the following equipment used by a DJ: Cartridge and stylus, Pickup arm, Turntables,
Mixer.
A turntable holds a record album and the pickup arm has the cartridge on the end with a stylus
which follows the grooves on the record.
2. Why cannot the output of the cartridge be connected directly to a mixing console?
needs a pre-amp
3. Why is it convenient to DI a synthesizer?
I don’t know that it is any more convenient to DI it than put a mic on the synth amplifier’s loud
speaker.
4. Comment on the stereo output of many synthesizers?
5. Why might it be desirable to amplify and mic up a synthesizer, as you would an electric
guitar?
to get the sound of the amp a synthesizer’s amp can be miked.
6. Comment on the use of loops in recording.
loops are used to create lengthier parts from shorter samples
7. Comment on tape loops.
tape loops are used the same way loops are but a tape is what the sample is on.
8. Comment on looping using a sampler and sequencer.
A sampler can be used to record a short section of an instruments sound and the sound can then
be imported to a sequencer so that it can be looped using cross fades.
9. Why is the sample looped using the sequencer in preference to looping it in the sampler?
A sampler usually does not have the amount of hard drive space needed for a loop of any
substantial length.
10. Comment on the significance of synchronizing the sequencer to multitrack tape.
If a sequencer is synchronized to a multitrack tape then the tape can be played, rewound, fast
forwarded, started or stopped using the sequencers commands.
If you want the sound on the sequencer to be on time with the other sounds on the tape then
synchronizing is necessary.
11. Comment on the suitability of audio sequencers for sample looping.
Sequencers are an excellent way to loop samples. although the sample would need to be
manipulated first in the sampler. For instance, the ADSR of the sample would have to be
adjusted first in the sampler.
12. What is timecode?
Time code is non musical data used to synchronize any MIDI controllable device
13. Comment on LTC, VITC and MTC.
LTC and VITC are the two ways to record SMPTE Time Code onto tape. MTC is a digital
conversion of the SMPTE that makes it possible for MIDI units to lock to SMPTE in real time.
14. Comment on MIDI Clock.
MIDI clock is dependent on the beat of the song. It understands music. Therefor if the song is
played faster than the clock moves faster.
15. Why is it desirable to synchronize two MIDI units via MIDI Clock?
To sync a drum machine or an effects unit to a sequencer.
So that the two devices can be used to control one another and stay in time.
16. How does MTC correspond to MIDI Clocks and Song Position Pointers?
It doesn’t ?
17. Why is it desirable to synchronize a sequencer to multitrack tape?
18. Comment on the two stages of building up a recording on multitrack tape with the aid of a
sequencer.
19. What is an audio sequencer?
A digital device used to record, edit, or play MIDI data .
20. Is an audio sequencer suitable as a replacement for a multitrack tape recorder (analog or
digital)? yes
21. Comment on the suitability of an audio sequencer for sample and loop editing?
A sequencer would probably be the preferred device for editing loops and samples.
22. Why is it not straightforward to synchronize an audio sequencer to multitrack tape?
The Sequencer sends MMC to the tape deck and the deck, being the master, sends MTC to the
sequencer.
23. What parameters of effects can often be controlled via MIDI?
The delay time of a delay unit can be controlled via MIDI
24. Why would you want to control effects parameters by MIDI?
If you wanted a delay to perfectly match time with the beat of a song or the automation feature of
a console can be controlled via MIDI
25. Does MTC come in all the frame rates of SMPTE/EBU timecode?
yes, 4 MTC time code frames per 1 SMPTE/EBU time code frame
26. Does MTC contain an address?
yes, System Exclusive Full Messages
27. Does MTC contain a clock?
yes, it is is in real time
28. Is MTC useful for synchronizing a MIDI sequencer?
yes
29. Is MTC useful for synchronizing digital audio?
yes
30. Is MTC useful for synchronizing analogue audio?
yes
31. Comment on the difference between standalone hard disk recorders and computer based hard
disk recorders.
Stand alone hard disc recorders have all that is needed to record where as the computer based
hard disc recorder is part of a complex computer system with more potential for problems.
32. Why is it a problem to use hard disks for long term storage?
expensive, constantly changing formats and archival stability not yet proven
33. Onto what media does backup/archival storage take place?
optical disc
34. What are the advantages of standalone hard disk recorders (compared to tape) for editing?
hard disc recorders are easier to edit on because there is no fast forwarding or rewinding and you
can cut and paste instead of bouncing.
35. What are the advantages and disadvantages of computer based hard disk recorders compared
to standalone hard disk recorders?
On a stand alone hard disc recorder the screen is very small but the internal parts are made to
work together. On a computer based system all the different devices used are not necessarily
going to be compatible.
36. Comment on the use of Pro Tools as an accessory to multitrack tape.
37. List the common digital multitrack tape formats and describe their characteristics.
ADAT is an 8 track system and DASH is a 24 or 48 track system. DAT is a stereo 2 track system
38. What is 'formatting'?
39. What are the advantages and disadvantages of digital multitrack compared to analogue
multitrack?
Advantages are cleaner sound, cheaper tapes
disadvantages, equipment incompatibility, glitches, no cut and splice capability
40. Compare the maintenance and cleaning of an analogue recorder to that of a digital recorder?
All the parts in the tapes path need to be cleaned regardless of the deck being analogue or digital
although the head on a digital recorder is rotating therefor is a little harder to clean.
41. Who carries out routine maintenance?
the recordist
42. Describe how the heads and guides of an analogue machine are cleaned. Mention the
materials used.
using a lint free material such as a foam swab with isopropyl alcohol
43. Describe how the pinch roller of an analogue machine is cleaned. Mention the materials used.
When cleaning the pinch roller a non alcohol based cleaner is used so as to not dry out the rubber
44. What are the effects of neglecting cleaning?
Noise on the recording and a muffled sound can be the effect as well as tape damage.
45. Why must an analogue machine be periodically demagnetized?
An increase in background noise and partial erasure of the higher frequencies can be the result of
a neglected machine. Oxide particles build up and the quality of the recording goes down
46. What happens if a machine is never demagnetized?
An increase in background noise and partial erasure of the higher frequencies will be the result.
47. What might happen if the demagnetized is operated incorrectly?
Incorrect operation can leave the heads and/or guides strongly magnetized.
48. Why do analogue tape recorders need to be lined up?
so that the tape travels evenly across the recorder head.
49. Do digital recorders ever need to be lined up?
yes
50. Comment on the three elements of line up.
Azimuth is adjusted by comparing the replayed phase of a test tone from top and bottom tape
tracks simultaneously, normally with the aid of an oscilloscope
Wrap and Zenith can be checked by marking the head with a special non-permanent dye and
running a blank tape over the head. Also using a test tape the bias and EQ can be checked and
adjusted
51. Explain the need for monitoring in sync.
When recording, monitoring is necessary so that all the devices in sync can be heard.
52. Why is the sync signal inferior to the playback signal?
The record head is used for playback in sync mode.
53. Why does this matter in track bouncing?
when bouncing, the levels of the track being bounced have to be set and therefor are set in stone.
The levels of the bounced track are set by listening to the monitored signal. If the signal is not an
accurate representation of the track then the adjustments that are made will be what is desired if
your lucky.
54. Is it possible to edit 2" analogue tape?
Yes, by cutting and splicing.
55. Is it possible to synchronize two 24-track recorders?
yes
56. Why is it often considered better to use an integrated disk recording system rather than one
that uses a personal computer as the user interface?
computers tend to crash and lock up
57. Comment on the presentation of some disk recorders as replacements for tape multitrack
recorders.
58. If a tape recorder has 24 inputs and 24 outputs, how many tracks will it have?
24
59. How many inputs and outputs would a disk recorder need if it was to be a replacement for a
24-track tape recorder?
24 inputs and 24 outputs
60. If a disk recording system had two inputs, two outputs, and was capable of twenty-four
tracks, what would be its main limitations?
61. What information is stored in the session file?
62. Are session files usually transportable between different systems?
no, they are system specific
63. Comment briefly on the suitability of SCSI, ATA and Firewire disks for audio recording.
FireWire is serial, as opposed to parallel tasking like SCSI, so data transfers over FireWire may
take
more CPU cycles to accomplish than when using SCSI. On older computers this can be a
problem, but
not so much now that 3 gigahertz-speed processors are so affordable.
64. What is 'fragmentation'?
Fragmentation is when clusters of information are spread out all over the disk. Fragmentation
occurs
naturally with everyday use. When files are deleted, a space is left behind and later filled with a
similar
size files. This is eventually leads to scattered information and a slower running computer.
65. Comment on archiving to CD-ROM.
CD-ROM files can be encoded in virtually any bit depth and sample rate. The CD-ROM disk’s
are
inexpensive and the technology is widely used.
66. What are 'virtual tracks'?
Virtual tracks are available on digital recorders. Each track would also have a set number of
virtual
tracks that can be used for second, third or forth takes for comparison purposes or to make room
for
another track to be recorded.
67. What is meant by 'edit density'? What are the implications of high edit density?
Edit density is a term used when describing the amount of edit points per second occurring
during
playback. High density, say like 2 edits per second, can result in halving the amount of tracks
able for
playback.
68. Does the editing and trimming of regions delete audio data from the disk?
as long as the undo feature is active, the last few trims are still on the disk and available for
recovery.
69. In editing, what is the difference between 'slip' and 'grid' modes?
These modes are found in Pro Tools.
"Slip" mode. This mode will allow you to move audio freely within your
session.
“Grid” mode is used well with drum beats because it keeps the regions in time on a user-set grid.
This
grid can be set to 1/4 notes, 1/2 notes or by milli- seconds.
70. When might it not be possible to create a crossfade?
When overlapping two region of sound to create a crossfade the timing of the song could be
affected if there are no handles on the regions.
71. What is 'bouncing', in the context of mixing?
Bouncing is when 2 or more tracks are combined on to another track. This is also an opportunity
to lay
down a live take on the same track at the same time as the bouncing.
72. What is meant by 'latency'?
Latency is the delay time between a sound entering the sound card and the sound coming back
out.
While using a computers operating system a signal is bound for latency. All systems suffer this
problem.
What is the difference between DSP processing and host-based processing?
Host based processing involves a computer, tends to have higher latency and doesn’t use DSP
chips. |
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Sun May 08, 2005 2:27 am |
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chemira
Joined: 03 Jan 2005
Posts: 50
Location: Nova Scotia Canada Eh! |
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A really big week here, please answer all completely.
1. Describe the following equipment used by a DJ: Cartridge and stylus, Pickup arm, Turntables, Mixer.
Cartridge –The cartridge is a transforms the vibration of the stylus into and electrical output.
Stylus- The stylus is the mechanism that is in contact with the groove in a record.
Pickup Arm-
Turntable- A DJ would use a direct drive turntable that would have a slip mat on top of the record platter so the DJ could cue up a track, mix or segment of an album.
Mixer- A DJ would use a mixer to blend fade or superimpose tracks from tape, vinyl or CD, samples beats or sequenced tracks along with voice or instruments.
2. Why cannot the output of the cartridge be connected directly to a mixing console?
The out put of a cartridge is not of a sufficient volume so it needs to be boosted and the EQ output of the album must be compensated for by boosting the low frequencies based on the RIAA curve of most albums.
3. Why is it convenient to DI a synthesizer?
A DI signal from a Synthesizer will posses a clean unaffected audio source that does not require any extra equipment like a Keyboard amplifier and a mic and cable.
4. Comment on the stereo output of many synthesizers?
Many synthesizers provide line level stereo outs or multiple outs that can be assigned for different voices. These assignable outputs can be grouped and sent to separate channels in a mixer.
5. Why might it be desirable to amplify and mic up a synthesizer, as you would an electric guitar?
By using an amplifier and microphone on a synthesizer they player can hear themselves play as if it were a monitor and the amplifier can impart a distinctive or different quality to the tone of the synthesizer.
6. Comment on the use of loops in recording.
Loops in recording can create multi layered complex patterns of quality instruments or sections of instruments without having to play, mic, and record the instruments. This technique is portable and very flexible in editing and sequencing software.
7. Comment on tape loops.
Tape loops are created by splicing the end and beginning of a section of tape together. The tapes loop size will be compensated by a remote capstan that will drive the tape not through the use of the reels themselves. [7]
8. Comment on looping using a sampler and sequencer.
Looping using a sampler can be done with a very precise manner if the loops are edited with care. The loop would be repeated at the end of every loop duration. The sequencer would load the same samples and trigger them at each desired start point.
9. Why is the sample looped using the sequencer in preference to looping it in the sampler?
A sequencer will keep the triggering of the sampled loop with more precision and without a shortening or lengthening of the relative time of the playback. If the loop has a small time difference the loop will be consistently triggered without timing errors.
10. Comment on the significance of synchronizing the sequencer to multi-track tape.
Without the synchronization of the sequencer to multi-track tape the relative timing would drift between the two devices. The sequencer would trigger at the appropriate time following the tape.
11. Comment on the suitability of audio sequencers for sample looping.
Audio sequencers are very flexible and powerful tools for sample looping. The tracks can be layered edited mixed faded or muted within the audio sequencer. Loops can further be edited precisely to create and combine new loops or layers.
12. What is timecode?
Time code is an embedded data signal that identifies the actual timing location that the master is at so that any other slave devices can playback, trigger or cue in accurate time. Any device that can send and receive time-code can be synchronized to other devices that send and receive time-code.
13. Comment on LTC, VITC and MTC.
LTC- Stands for longitudinal time code which is one of two SMPTE (Society of Motion Picture and Television Engineers) standards. It is called longitudinal because the time code is stamped along the length of the tape.
VITC-Is an acronym for Vertical Interrupt Time Code. This Time code is embedded on the video track used in Beta or DigiBeta formats. The time code represents a specific Address reference for synchronization.
MTC-MIDI Time code is based on reference beats from the beginning of a song that will synchronize two devices together using SysEx Messages.
14. Comment on MIDI Clock.
MIDI Clock provides 96 clocks per 4 beat bar. The tempo of the master device will determine the speed of the slave devices. This Clock is utilized in the tempo maps of Drum machines.
15. Why is it desirable to synchronize two MIDI units via MIDI Clock?
By synchronizing two MIDI units via MIDI Clock the slave device will respond in synchronization with the master device creating a very tightly played back segment of MIDI music.
16. How does MTC correspond to MIDI Clocks and Song Position Pointers?
17. Why is it desirable to synchronize a sequencer to multitrack tape?
The Sequencer can quickly respond to slight variations in the Multitrack tape faster than the tape could respond to the sequencer. Tape may stretch or motors timing may become off.
18. Comment on the two stages of building up a recording on multitrack tape with the aid of a sequencer.
By utilizing the sequencer to create an already planned tempo map to the tape on the first pass then use the tape as the master so that the sequencer follows for the second stage of overdubbing.
19. What is an audio sequencer?
An audio sequencer is a software based program that has the capabilities to record, edit, manipulate, and arrange sound samples as loops or complete tracks. The program requires the ability to deal with triggering audio to define it as sequencing program. Cubase Sonar or Logic Audio are Audio Sequencers.
20. Is an audio sequencer suitable as a replacement for a multitrack tape recorder (analog or digital)?
Yes an audio sequencer is suitable as a replacement for a multi track recorder since it has all of the capabilities but not necessarily the sound qualities.
21. Comment on the suitability of an audio sequencer for sample and loop editing?
An audio sequencer has all of the capabilities along with visual editing and loop editing capabilities.
These factor allow the audio sequencer to be a powerful tool to facilitate loop editing.
22. Why is it not straightforward to synchronize an audio sequencer to multitrack tape?
Multi track tape does not have a time code already on it when it is new therefore the recording engineer must record or stamp the time code on the multitrack tape so that other devices can later be synchronized to it for playback and at mixdown.
23. What parameters of effects can often be controlled via MIDI?
Parameters of effects that are often controlled by MIDI are volume, send, pan and mute automation.
24. Why would you want to control effects parameters by MIDI?
MIDI effects control will allow synchronization of the effects to a time code so that consistent playback of the automated mix will occur.
25. Does MTC come in all the frame rates of SMPTE/EBU timecode?
Yes MTC comes in all four frame rates of SMPTE/ EBU 30 fps 29.97 fps 25 fps and 24 fps.
26. Does MTC contain an address?
27. Does MTC contain a clock?
MTC responds to and references itself to a time of day time stamp, not a clock.
28. Is MTC useful for synchronizing a MIDI sequencer?
Yes, you can use MTC to synchronize devices that are using SMPTE as their time code.
29. Is MTC useful for synchronizing digital audio?
Again , yes you can use MTC to synchronize digital devices that use MTC like a timing clock master synchronizing hard disc recorders together.
30. Is MTC useful for synchronizing analogue audio?
Yes MTC can be used to synchronize analogue multi-track devices that utilize MTC format as their means of synchronization.
31. Comment on the difference between standalone hard disk recorders and computer based hard disk recorders.
A standalone hard disc recorder is designed to record the specified number of tracks at the highest audio bit depth and frequency without any problems. The Computer based system has no definite track count and the recording playback track count is subject to the performance of the computer, the state of the drives or the extra effects that are utilized. Standalone has limits to tracks but is very stable. The Computer may have extra potential but is not as reliable and requires more maintenance.
32. Why is it a problem to use hard disks for long term storage?
They are not proven for long term storage, they have failures and the format does change as computer architecture advances which makes upgrade storage more expensive if you want current archive access of all of the information.
33. Onto what media does backup/archival storage take place?
Long term storage is being done with the CDR and now the higher capacity DVD. They are very stable as long as they are stored correctly and they are very inexpensive.
34. What are the advantages of standalone hard disk recorders (compared to tape) for editing?
A standalone hard disc recorder can rearrange the tracks or segments of tracks, cut copy and paste features are usua | | | |
